Hey guys, I was hoping I could get some info from you guys. This is a long post but it's an interesting one.
So my Marshall MG100HDFX head has a blown TDA7293 chip and thanks to the info I found on this forum I was able to find and order a replacement TDA7293 PCB assembly from Antique Electronic Supply. So I installed the replacement in my amp (used thermal compound, replaced fuse, cabled everything correctly to my MG speaker cab etc.) and it blew again, but this time a small capacitor on the PCB board exploded. I watched it happen because I had the amp assembly outside of the head when I powered it on.
This is what it looked like after I took it out of my amp:
I then realized that the wiring on the replacement they sent me was backwards and thought maybe this is what caused it to fail. So I did some research on why capacitors explode and found out that its due to backwards wiring because some capacitors are "polarized" and can only be used one way, so when they're wired backwards they can fail and explode.
This is a picture of the stock TDA7293 PCB assembly that came with my amp with the correct wiring of a yellow wire on the far left and a black wire on the far right(I already removed the TDA7293 chip on it BTW):
As you can see in the picture, the wire on the far left is yellow and the wire on the far right is black. This is the correct wiring because my amp worked fine until it blew due to a friend incorrectly cabling it when recording. If you go to the Antique Electronic Supply website, you can see in the picture they have that the PCB assembly is wired like this as well. All of the pictures I have found online of the TDA7293 PCB assembly have this same wiring pattern so I'm pretty confident that this is the correct wiring pattern.
So I contacted Antique Electronic Supply and told them that the part failed because it was wired backwards so they sent me another replacement and...........lo and behold this one was ALSO wired backwards.
Here is a picture of the second replacement part they sent me, pay attention to the wiring and compare to the one above:
As you can see, the wiring is backwards. So my question to you guys is am I right about the wiring? Does it matter if the wiring is backwards? I'm no expert, but I'm pretty sure it does matter because the colors of the wires represent different things like positive and negative charges so when it's wired incorrectly and connected to the mainboard of my amp it will blow, right? Hopefully some of you with more knowledge would be able to give me more info.
I'm not going to install this second replacement they sent me because I'm pretty sure it will blow again. Let me know what you guys think!
So my Marshall MG100HDFX head has a blown TDA7293 chip and thanks to the info I found on this forum I was able to find and order a replacement TDA7293 PCB assembly from Antique Electronic Supply. So I installed the replacement in my amp (used thermal compound, replaced fuse, cabled everything correctly to my MG speaker cab etc.) and it blew again, but this time a small capacitor on the PCB board exploded. I watched it happen because I had the amp assembly outside of the head when I powered it on.
This is what it looked like after I took it out of my amp:
I then realized that the wiring on the replacement they sent me was backwards and thought maybe this is what caused it to fail. So I did some research on why capacitors explode and found out that its due to backwards wiring because some capacitors are "polarized" and can only be used one way, so when they're wired backwards they can fail and explode.
This is a picture of the stock TDA7293 PCB assembly that came with my amp with the correct wiring of a yellow wire on the far left and a black wire on the far right(I already removed the TDA7293 chip on it BTW):
As you can see in the picture, the wire on the far left is yellow and the wire on the far right is black. This is the correct wiring because my amp worked fine until it blew due to a friend incorrectly cabling it when recording. If you go to the Antique Electronic Supply website, you can see in the picture they have that the PCB assembly is wired like this as well. All of the pictures I have found online of the TDA7293 PCB assembly have this same wiring pattern so I'm pretty confident that this is the correct wiring pattern.
So I contacted Antique Electronic Supply and told them that the part failed because it was wired backwards so they sent me another replacement and...........lo and behold this one was ALSO wired backwards.
Here is a picture of the second replacement part they sent me, pay attention to the wiring and compare to the one above:
As you can see, the wiring is backwards. So my question to you guys is am I right about the wiring? Does it matter if the wiring is backwards? I'm no expert, but I'm pretty sure it does matter because the colors of the wires represent different things like positive and negative charges so when it's wired incorrectly and connected to the mainboard of my amp it will blow, right? Hopefully some of you with more knowledge would be able to give me more info.
I'm not going to install this second replacement they sent me because I'm pretty sure it will blow again. Let me know what you guys think!
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